Grenades are useful tools for clearing out pools of enemies and also taking out enemies behind cover, however, I rarely see people using the grenade that effectively. Everybody knows that place on Gibraltar which is in the middle toll station with what looks like a bunker. If you do not have rockets you can use a grenade to clear out enemies on top and you can do it without throwing your grenade right up into the air.

Controlling power of throw: To neutralize enemies behind this wall (and plenty of other places) you have to use the right mouse button instead, the longer you hold down the right mouse button, the greater the power of the through. The power of which the grenade has should be indicated on the bottom right corner HUD. At near halfway, release the grenade and watch it go just over the wall and neutralize all enemies on the other side. Controlling the power of a throw will allow you to neutralize enemies in the same situation, however you may need to incorporate a jump in order for it to go over the cover or wall.

Jumping: Jumping can help you increase the distance and height of your grenade, use it when you want it to go a little farther than usual with you grenade. Also include a simultaneous jump when performing power throws over walls or cover, because if you don't you find yourself killed by your own grenade.

Reflecting your throw: In some cases the enemy will be at such an angle or at elevation that by simply throwing your grenade a little higher won't do anything. You need to use objects in this case to reflect your grenade into the enemies lap. An example of this is when you are in a titan corridor, an enemy is positioned close to the door, by moving in front of him and throwing the grenade at him, he'll usually escape before your grenade explodes and kill you too. So step as far to the left of the corridor entrance, the toss the grenade at the wall, it should reflect toward the enemy and kill him. When doing this you have to make sure the grenade hits the right angle, otherwise it'll bounce off the wall to you again.

It would be a lot better if players started using their grenades more effectively like this, then they can stay alive more and neutralize enemies behind cover which they think they are protected behind. These grenade skills can be very helpful in breaching enemy areas.